This invention relates to a flexible damped bearing and, in particular, to means for supporting the dead weight of the rotor within the bearing system.
A flexible damped bearing concept for overcoming instability in a rotor assembly of an engine is disclosed in NASA Technical Note D-7892, published Feb. 1975, and in U.S. Pat. No. 3,456,992, to Kulina. As disclosed by Kulina, the shaft of a turboengine is rotatably supported within the engine frame by means of a roller bearing. The bearing, in turn, is mounted within a movable support member that is suspended from the engine frame via a series of flexure springs. The flexure spring support provides the bearing assembly with a mechanical response which attenuates the harmful effects of shaft vibrations. A fluid film is also established between the flexible mounted bearing support and the engine frame which serves to dampen the system's response to shaft induced vibrations.
Difficulties have been encountered when applying the flexible damped bearing concept to heavy rotary machines, such as turbines and compressors. For the bearing to react in a controlled manner, it is essential that the bearing components be assembled in axial alignment with the shaft to preserve the uniformity of the squeeze film and insure that the flexure springs react symmetrically. In most rotary machines, however, the heavy rotor structure is suspended horizontally within the machine frame and the dead weight of the rotor exerts a high static preload upon the bearing system which, in turn, places a nonuniform stress on the bearing. Under these conditions, proper alignment of the bearing components in assembly becomes difficult.